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Biomedical subjects

L Pollack

Publications and source records attributed to L Pollack.

At least 19 recordsLinked to original sources
PubMed2005

Bringing HIV/STI testing programmes to high-risk men.

The aim of this study was to examine the meaning of significantly higher proportions of positive test results through outreach HIV/sexually transmitted infection testing programmes at gay bathhouses compared with clinic programmes among high-risk men who have sex with men. We conducted a random digit dial survey of men who have sex with men in New York, Los Angeles, Chicago, and San Francisco. Half of the men in the sample did not test in the past year. Among those who did not test, a sizeable minority (17%) reported engaging in high-risk sexual behaviour with a casual or secondary partner. Over half of these non-testing, high-risk men went to bathhouses. These findings strongly support the potential value of locating outreach-testing programmes in bathhouses. Although further studies are necessary, such programmes have the potential to increase testing among the high-risk segment of the population. This is particularly noteworthy given that many men among those who do not test regularly engage in high-risk behaviours.

AIDS Serodiagnosis↗
PubMed2004

Spatial distribution of competing ions around DNA in solution.

The competition of monovalent and divalent cations for proximity to negatively charged DNA is of biological importance and can provide strong constraints for theoretical treatments of polyelectrolytes. Resonant x-ray scattering experiments have allowed us to monitor the number and distribution of each cation in a mixed ion cloud around DNA. These measurements provide experimental evidence to support a general theoretical prediction: the normalized distribution of each ion around polyelectrolytes remains constant when ions are mixed at different ratios. In addition, the amplitudes of the scattering signals throughout the competition provide a measurement of the surface concentration parameter that predicts the competition behavior of these cations. The data suggest that ion size needs to be taken into account in applying Poisson-Boltzmann treatments to polyelectrolytes such as DNA.

Cations↗
PubMed2003

Counterion distribution around DNA probed by solution X-ray scattering.

Counterion atmospheres condensed onto charged biopolymers strongly affect their physical properties and biological functions, but have been difficult to quantify experimentally. Here, monovalent and divalent counterion atmospheres around DNA double helices in solution are probed using small-angle x-ray scattering techniques. Modulation of the ion scattering factors by anomalous (resonant) x-ray scattering and by interchanging ion identities yields direct measurements of the scattering signal due to the spatial correlation of surrounding ions to the DNA. The quality of the data permit, for the first time, quantitative tests of extended counterion distributions calculated from atomic-scale models of biologically relevant molecules.

Cations↗
PubMed2001

National trends in condom use among at-risk heterosexuals in the united states.

Based on national level surveys, we examined data relevant to the United States' overall effort to prevent the spread of HIV among heterosexual adults. We examined changes in condom use among at-risk heterosexuals over the past decade. The observed increases over time in condom use across all heterosexual at-risk population segments are consistent with the observed (declines) trends in HIV and syphilis in the 1990s. These results and findings from prior studies suggest that U.S. efforts to facilitate condom use and contain HIV and related sexually transmitted disease (STD)-cofactors among adult at risk heterosexuals was succeeding over most of the 1990s. The absence of national level behavioral trend data after 1996, and the ambiguities of HIV spread suggest some caution in projecting trends into this century. National and local efforts need to be directed at sustaining behavioral change and conducting more rigorous studies on population trends in HIV/STD-related behaviors/pathogens.

Adolescent↗
PubMed2001

Time resolved collapse of a folding protein observed with small angle x-ray scattering.

High-intensity, "pink" beam from an undulator was used in conjunction with microfabricated rapid-fluid mixing devices to monitor the early events in protein folding with time resolved small angle x-ray scattering. This Letter describes recent work on the protein bovine beta-lactoglobulin where collapse from an expanded to a compact set of states was directly observed on the millisecond time scale. The role of chain collapse, one of the initial stages of protein folding, is not currently understood. The characterization of transient, compact states is vital in assessing the validity of theories and models of the folding process.

Animals↗
PubMed2001

Understanding childhood sexual abuse as a predictor of sexual risk-taking among men who have sex with men: The Urban Men's Health Study.

OBJECTIVE: The prevalence and characteristics of childhood sexual abuse (CSA) among men who have sex with men (MSM), and links with sexual risk are explored. A model linking CSA and sexual risk among MSM is proposed. METHOD: A telephone probability sample of urban MSM (n = 2881) was recruited and interviewed between November 1996 and February 1998. The interview covered numerous health issues, including history of sexual victimization. RESULTS: One-fifth reported CSA, primarily by non-family perpetrators. Initial CSA experiences are characterized by high levels of force (43% involved physical force/weapons), and penetrative sex (78%; 46% reported attempted or actual anal intercourse). Such men are more likely than nevercoerced men to engage in high risk sex (unprotected anal intercourse with a non-primary partner or with a serodiscordant male). In multivariate analyses, the effect of childhood sexual coercion on sexual risk is mediated by substance use, patterns of sexual contacts, and partner violence, but not by adult sexual revictimization or by depression. CONCLUSIONS: Findings are interpreted within the context of social learning theory and prior research on sexual risk-taking. The high risk for CSA among MSM, which can predispose such men to patterns of HIV sexual risk, warrants new approaches in HIV prevention.

Adolescent↗
PubMed2001

Use of antiretroviral therapies among HIV-infected men who have sex with men: a household-based sample of 4 major American cities.

OBJECTIVES: This study sought to determine the prevalence and determinants of use of recommended antiretroviral regimens among urban seropositive men who have sex with men (MSM). METHODS: A probability telephone sample of MSM was taken within regions of Chicago, Los Angeles, New York, and San Francisco. Analysis focused on use of antiretroviral therapies. RESULTS: Although the majority of seropositive MSM with CD4 counts below 500 per microliter were using recommended antiretroviral regimens, 26% of seropositive MSM were not receiving such care. Men who were younger, who reported a sexual orientation other than homosexual, who had a more recent interview date, who were at middle levels of affiliation with the gay community, and who reported higher levels of perceived exclusivity on the part of the gay community were less likely to be using recommended antiretroviral regimens. CONCLUSIONS: Although current efforts to make antiretroviral therapies available to HIV-seropositive MSM are reasonably effective, additional efforts are needed for MSM characterized by relative youth and lower social support.

Adolescent↗
PubMed2001

The continuing HIV epidemic among men who have sex with men.

OBJECTIVES: This study characterized the AIDS epidemic among urban men who have sex with men (MSM). METHODS: A probability sample of MSM was obtained in 1997 (n = 2881; 18 years and older) from New York, Los Angeles, Chicago, and San Francisco, and HIV status was determined through self-report and biological measures. RESULTS: HIV prevalence was 17% (95% confidence interval = 15%, 19%) overall, with extremely high levels in African Americans (29%), MSM who used injection drugs (40%), "ultraheavy" noninjection drug users (32%), and less educated men (< high school, 37%). City-level HIV differences were non-significant once these other factors were controlled for. In comparing the present findings with historical data based on public records and modeling, HIV prevalence appears to have declined as a result of high mortality (69%) and stable, but high, incidence rates (1%-2%). CONCLUSIONS: Although the findings suggest that HIV prevalence has declined significantly from the mid-1980s, current levels among urban MSM in the United States approximate those of sub-Saharan countries (e.g., 14%-25%) and are extremely high in many population subsegments. Despite years of progress, the AIDS epidemic continues unabated among subsegments of the MSM community.

Adolescent↗
PubMed2001

Health-related characteristics of men who have sex with men: a comparison of those living in "gay ghettos" with those living elsewhere.

OBJECTIVES: This study investigated the limitations of probability samples of men who have sex with men (MSM), limited to single cities and to the areas of highest concentrations of MSM ("gay ghettos"). METHODS: A probability sample of 2881 MSM in 4 American cities completed interviews by telephone. RESULTS: MSM who resided in ghettos differed from other MSM, although in different ways in each city. Non-ghetto-dwelling MSM were less involved in the gay and lesbian community. They were also less likely to have only male sexual partners, to identify as gay, and to have been tested for HIV. CONCLUSIONS: These differences between MSM who live in gay ghettos and those who live elsewhere have clear implications for HIV prevention efforts and health care planning.

AIDS Serodiagnosis↗
PubMed2001

Differential HIV risk in bathhouses and public cruising areas.

OBJECTIVES: This report investigates differences in risk behaviors among men who have sex with men (MSM) who went to gay bathhouses, public cruising areas, or both. METHODS: We used a probability sample of MSM residing in 4 US cities (n = 2,881). RESULTS: Men who used party drugs and had unprotected anal intercourse with nonprimary partners were more likely to go to sex venues than men who did not. Among attendees, MSM who went to public cruising areas only were least likely, and those who went to both public cruising areas and bathhouses were most likely to report risky sex in public settings. CONCLUSIONS: Distinguishing between sex venues previously treated as a single construct revealed a significant association between pattern of venue use and sexual risk. Targeting HIV prevention in the bathhouses would reach the segment of men at greatest risk for HIV transmission.

Adolescent↗
PubMed2000

Health care policy. U.S. priorities-HIV prevention.

One of the scientific anomalies of the AIDS epidemic is the large difference in infection rates across populations. Given limited resources and segregated epidemics, prevention funding should be directed to population segments with high HIV prevalence and incidence. However, recent surveys of U.S. populations indicate that the allocation of prevention dollars is not consistent with the distribution of HIV in the population.

Disease Outbreaks↗
PubMed2000

Obtaining HIV test results with a home collection test kit in a community telephone sample.

OBJECTIVES: To test the feasibility of obtaining HIV test results by home collection kit from a probability telephone sample of men who have sex with men (MSM). METHODS: A quota sample of 615 MSM previously interviewed by the Urban Men's Health Study phone survey in Chicago, Los Angeles, New York City, and San Francisco were re-contacted and offered an HIV test using an oral specimen (Orasure) home collection kit. RESULTS: Eighty percent consented to be mailed a kit, and 84% returned a specimen, for a 67% participation rate. All self-reported HIV-positive persons tested positive (77 of 77); 4 of 266 (1.5%) with a prior negative test and 2 of 69 (2.9%) with no prior positive HIV test result. Participation was associated with self-reported prior HIV test status-HIV-positive (83%), HIV-negative (68%), or no prior HIV test result (54%)-and marginally associated with New York City residence after adjustment for HIV status (odds ratio = 0.7; 95% confidence interval, 0.4-1.1; p =.08). CONCLUSIONS: These results suggest that urban MSM identified and interviewed by telephone will participate in home collection HIV testing. This methodology could be used to produce population-based estimates of HIV seroprevalence and seroincidence in MSM and could probably be extended to other populations and other viral infections.

AIDS Serodiagnosis↗
PubMed1999

Compactness of the denatured state of a fast-folding protein measured by submillisecond small-angle x-ray scattering.

Time-resolved small-angle x-ray scattering was used to measure the radius of gyration of cytochrome c after initiation of folding by a pH jump. Submillisecond time resolution was obtained with a microfabricated diffusional mixer and synchrotron radiation. The results show that the protein first collapses to compact denatured structures before folding very fast to the native state.

Crystallography, X-Ray↗
PubMed1995

[Ciprofloxacin-associated bilateral acute achilles tendinitis].

Bilateral achilles tendinitis developed in a 40-year-old man following treatment with Ciprofloxacin, 500 mg twice a day, for prostatis. The signs of tendinitis resolved 6 weeks after cessation of the drug. In recent years very few cases of this rare complication have been reported. In some cases it results in a torn achilles tendon. If diagnosed early, complete recovery usually follows about 6 weeks after cessation of the drug.

Achilles Tendon↗
PubMed1993

Disclosing HIV seropositivity to significant others.

OBJECTIVES: To examine gay men's patterns of self-disclosure of HIV seropositivity to friends, lovers, relatives and colleagues; to assess the effects of disclosure; and to identify reasons for not disclosing to particular individuals. DESIGN: Longitudinal questionnaire survey of gay men. METHODS: A total of 163 HIV-positive men participating in the AIDS Behavioral Research Project, a longitudinal study of San Francisco gay men, completed questionnaires about their self-disclosure patterns, health status, and psychological well-being. RESULTS: HIV-positive men were most likely to disclose their status to lovers and closest gay friends. Asymptomatic men were less likely to disclose to relatives and colleagues than symptomatic men. Friends and lovers were rated as responding more helpfully than relatives and colleagues. Men who perceived their significant others as responding more helpfully were less depressed and anxious currently and 1 year later. A variety of reasons were given for not disclosing, including not wanting to worry others, fear of discrimination, fear of disrupting relationships, and emotional self-protection. CONCLUSION: While disclosure can have advantages for both HIV-positive individuals and their significant others, HIV-positive individuals must be assured that the benefits of doing so will outweigh the potential costs.

Adult↗